Rzetnia was formerly part of the German Empire. In the German Empire, the place was called Mühlbach.
The place is now called Rzetnia and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Rzetnia | German Empire | Kempen i. Posen | before the Versailles Treaty |
| Rzetnia | Poland | Kępno | after the Versailles Treaty |
| Mühlbach | German Empire | Kempen (Wartheland) | 1939 |
| Rzetnia | Poland | Kępno | 1945 |
| Rzetnia | Poland | Kalisz | 1992 |